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Basic Question About How A Pir Works


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Posted

I am working with a Pyronix KX15DT unit and want to understand its workings.

There are 6 terminals - 2 for power, 2 for alarm and 2 for tamper.

Am I correct in assuming that behind the tamper connection is simply a closed relay point which opens when the unit is opened? i.e. normally closed

Am I correct in assuming that behind the alarm connections is a normally closed relay point which opens when the unit detects movement?

Ken

Posted

Excellent. Thank you for that Rich.

Now, take the situation where I only have two wires going to the PIR (plus of course two for power).

I define the Zone in the panel as Dual End of Line Wiring. The panel book advises use of 4K7 resistors for this setup.

So the PIR now has a 4K7 resistor in series with the normally closed tamper relay.

It has also a 4K7 resistor in parallel with the normally closed alarm contact.

Then, if the panel is NOT armed, it should tolerate seeing either 4K7 or 9K4 and not alarm. This is becaues movement may open the alarm circuit.

If the panel IS armed, then it will expect to see only 4K7. If it sees 9K4 then it should alarm.

And finally if it ever sees open circuit, it should tamper alarm.

Have I got all that correct?

Ken

Posted

Yep again, sounds all good to me,(Apart from the bit where you said 'if it see's no resistance it will come up as tamper')-Don't tell me thats what you were gonna say next ! :rolleyes: .

Rich.

As Redbull suggests check the resistor values-don't know the panel particularly so I can't comment.

Posted

Thats the beauty of a community such as this-ask a question and someone will answer it-we all have certain skills.

Any more for tonight or can i go to bed now :rolleyes: .

All the best.

Rich.

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